Transconductance cells are typically employed as building blocks in the design of complex electronic circuits, or systems. There are many types of transconductance cells available to circuit designers, each with different characteristics and topologies. Some of the desirable characteristics of transconductance cells are low noise, low power consumption, linearity, and size. As is common in circuit design, however, transconductance cells with topologies that optimize one characteristic may be degrade one or more of the other characteristics. For example, a transconductance cell configured for low power consumption may have worse linearity than a cell configured for higher power consumption.
Systems that include multiple transconductance cells, such as filters, typically use the same topology for all of their cells throughout their design. This uniformity in cell type ensures that the transconductance cells track each other when adjusted with a common bias voltage or current. FIG. 1 shows a typical system of transconductance cells 100. Referring to FIG. 1, the system 100 includes a plurality of transconductance (gm) cells 120-1 to 120-N. The gm cells 120-1 to 120-N are the same type, i.e., they have the same topology or configuration, and thus track each other when adjusted by a common bias voltage 112 (or current).
A transconductor tuning loop 110 generates and provides the common bias voltage 112 to each of the gm cells 120-1 to 120-N. The transconductor tuning loop 110 generates the common bias voltage 112 by adjusting the transconductance of a tuning gm cell 111 with the same topology as the gm cells 120-1 to 120-N. Once adjusted, the gm cells 120-1 to 120-N track the tuning gm cell 111. Although system 100 has the advantage of tracking all of the transconductance cells 120-1 to 120-N with a common tuning loop 110, the use of a single cell-topology limits the ability of designers to advantageously incorporate and track differing cell types into their designs.